Disease at the carotid bifurcation: diagnosis by Doppler ultrasound imaging

A non-invasive method for visualising the carotid bifurcation using continuous-wave Doppler-shift ultrasound and spectral analysis is described. The system is directional so that arteries can be visualised without interference by signals from adjacent veins. The technique uses a transducer attached to a position-sensing arm so that the position of arterial flow-velocities can be translated onto a storage oscilloscope. A two dimensional image of the carotid bifurcation is formed by moving the transducer along the length of each vessel while repeatedly scanning across the vessel lumen. The clinical application of this technique is illustrated by some specific cases.